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Publication Abstract from PubMed

Synaptotagmins constitute a family of multifunctional integral membrane proteins found predominantly on vesicles in neural and endocrine tissues. 17 isoforms of synaptotagmin family in mammals have been identified, 7 isoforms among them are known to be able to bind Ca2+ via their C2 domains. This study presents the crystal structure of the first C2 domain (C2A domain) of synaptotagmin 5 complexed with Ca2+ at 1.90A resolution. Comparison of the Ca2+-binding pocket of synaptotagmin 5 C2A domain with other synaptotagmin C2 domains demonstrated that a serine residue locating at Ca2+-binding loop probably responsible to the conformational variation of Ca2+-binding pocket, and thus impacts the Ca2+-binding mechanism of C2 domain, which is verified by structural analysis of the serine mutant and Ca2+-binding assays via isothermal titration calorimetry. Alteration of Ca2+-binding mechanism might be correlated with different Ca2+ response rates of synaptotagmins, which is the basis of the functions of synaptotagmins in regulating various types of Ca2+-triggered vesicle-membrane fusion processes.

Structural analysis of Ca2+-binding pocket of synaptotagmin 5 C2A domain.,Qiu X, Ge J, Gao Y, Teng M, Niu L Int J Biol Macromol. 2016 Oct 25. pii: S0141-8130(16)32153-5. doi:, 10.1016/j.ijbiomac.2016.10.083. PMID:27793683^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.